code: def sqrt(expr):
      return ast.PowExpr(base_expr=expr, exp_expr=ast.NumVal(0.5))
  
file_path: m2cgen/m2cgen/assemblers/fallback_expressions.py
imports: import math
  from m2cgen import ast
  from m2cgen.assemblers import utils
label_desc: Use image node_id 3 for calling a global function with example usage: sqrt(expr) and returns: ast